Experimental Poverty Measures, 2010: Public-Use Dataset Notes
These notes are for analysts who use the public-use file that contains
alternative poverty estimates for calendar year 2010 and other variables
related to poverty measurement. Corresponding data based on the U.S. Census
Bureau's internal datafiles may be found at
http://www.census.gov/hhes/povmeas/data/nas/tables/2010/index.html
The estimates included in these files are an update of the estimates in the
report P60-227 (Alternative Poverty Estimates in the United States: 2003 --
available at http://www.census.gov/prod/2005pubs/p60-227.pdf)that were based on recommendations from a National Academy of Sciences (NAS)panel.
Three files are available from the U.S. Census Bureau's Experimental Poverty
Measurement site at http://www.census.gov/hhes/povmeas/data/public-use.html:
1. povpu10.sas7bdat
2. povpu10.sas
3. povpu10.lst
The SAS dataset, povpu10.sas7bdat, was created using SAS version 9.2 on a UNIX platform. Contained in the SAS dataset are variables used to construct these experimental poverty measures. For details about the construction of the measures and their component elements, please refer to the P60-227 report
(referenced above) and to P60-205, Experimental Poverty Measures: 1990 to 1997 (available at http://www.census.gov/prod/99pubs/p60-205.pdf), especially
Appendix C.
All variables in the public-use SAS dataset have variable labels, and, where
appropriate, value labels. Household, family, and person-level ID variables are also contained in the dataset to allow analysts to re-merge the file with the 2011 Current Population Survey Annual Social and Economic Supplement (CPS ASEC) public-use file from which the datasets were created.
The SAS program povpu10.sas reads in the SAS dataset, and, for illustrative
purposes, also displays the final SAS data steps used to create the experimental poverty measures already contained in the dataset. (The recodes testpoor1 - testpoor13, created within the program, replicate poor1 - poor13 which are already on the file.) These steps are shown to help analysts replicate the experimental poverty measures and to provide guidance for those who wish to appropriately recombine various elements (i.e., thresholds and income definitions) to view alternative poverty measures.
Notes:
1. NEW METHOD FOR TOPCODING INCOME AND RELATED VARIABLES ON THE PUBLIC-
USE FILE
Creation of the Experimental Poverty Measures public-use data file reflects new disclosure avoidance methods for dollar values. These methods have traditionally been termed “topcoding” procedures as income amounts above specified levels have been changed to prevent individual from being identified (disclosure) based on the value.
Until 2011 the topcoding method has either changed amounts above a specified
topcode value at that value or substitutes the mean value of all amounts above the topcode (termed topcode cutoff). These methods have been replaced by methods that swap values between sample cases having incomes above the topcode. This method of topcoding preserves the distribution of values above the topcode while maintaining adequate disclosure avoidance.
The technique used for swapping values is termed “rank proximity swapping”. Once the topcode has been established, all persons with value above the topcode cutoff are sorted by those values from lowest to highest (values equal to the specified topcode are included in the universe of those requiring topcoding). Next the values above the topcode are systematically swapped between sample persons. The swapping occurs within a bounded interval. This bounded interval assures that the values swapped are in “proximity” to each other, yet providing a sufficiently large group of persons from which the swap partners are selected. The use of swapping techniques is accompanied by the procedure to round the swapped amounts.
All topcoded amounts included on the public-use file are rounded to two significant digits (i.e. $987,654=$990,000; $12,345=$12,000; $9,870=$9,900). Rounded values will never exceed the maximum value on the file (i.e. $999,999=$999,999).
Note that the data after topcoding were used to create all combined income recodes on the file. This means, for example, that one’s total income amount may include a topcoded amount among the income sources in the calculation. Therefore, the total income amount may seem high when analyzing family poverty ratios.
2. INCOME VARIABLE AND SWAPPED VARIABLE CAVEATS:
It is important to note that many of the poverty rates generated using these public-use SAS datasets differ slightly from those shown in Census Bureau publications. These differences occur because some public-use variables (such as the variables for total income, income by source, taxes, family medical out-of-pocket expenditures, and the amounts of child care expenses paid, and child support paid) are swapped and rounded to protect respondents' confidentiality.
Therefore, when computing alternative resource definitions--which by necessity use topcoded variables as components--please bear these differences in mind.
3. 2010 INCOME
In an effort to expedite the release of alternative income and poverty estimates the March 2011 CPS ASEC Public Use File has been released without estimates for capital gains and capital losses. For this reason poverty estimates for 2010 are not strictly comparable to estimates from previous years.
In 2009 and 2010, the Making Work Pay provision of the American Recovery and Reinvestment Act of 2009 provided a refundable tax credit of up to $400 for working individuals and up to $800 for married taxpayers filing joint returns. The Making Work Pay credit was included in the calculation of federal taxes (ffedtax) and is not listed as a separate variable in this datafile. This credit was given to all wage earners as an adjustment on their paycheck withholdings, or for self-employed earners as a credit claimed on their taxes. This tax model uses the tax credit computations for all earnings, which results in the same credit as the adjustment.
4. GEOGRAPHIC VARIABLE CAVEATS:
Three issues with geographic variables warrant the user's attention: a change in sample design in the CPS ASEC public-use file meant that complete information on metropolitan/nonmetropolitan status was not available for every area; a change in geographic concepts prompted a new set of geographic variables; and last, the geographic-adjustment indices for poverty thresholds (geo2) were constructed with estimated metropolitan status information and with appropriate suppression of confidential data.
See P60-216, Experimental Poverty Measures: 1999 for further information on the methods used to construct the geographic indices for the poverty thresholds at: http://www.census.gov/prod/2001pubs/p60-216.pdf.